diff --git a/linebot_app.py b/linebot_app.py
index f8a7ccb..0969181 100755
--- a/linebot_app.py
+++ b/linebot_app.py
@@ -36,6 +36,16 @@ from linebot.v3.messaging import (
 
 app = Flask(__name__)
 
+# logging
+log_file_name = "./linebot.message.log"
+
+# initiate log file
+log_file = open(log_file_name, "w")
+log_file.write("")
+log_file.close()
+
+
+
 # User Sessions
 user_sessions = {}
 
@@ -94,12 +104,13 @@ def callback():
 @handler.add(MessageEvent, message=TextMessageContent)
 def message_text(event):
 
+    log_file = open(log_file_name, "a")
+    log_file.write("user_id: " + event.source.user_id + ", time: " + event.timestamp + ", message:" + event.message.text)
     # User Session
     # create session if none exist
     if event.source.user_id not in user_sessions.keys():
         user_sessions[event.source.user_id] = ConversationalRetrievalChain.from_llm(llm,retriever=retriever,memory=ConversationBufferMemory(memory_key="chat_history", return_messages=True))
     
-    print(event.source.user_id, ":", event.message.text)
     # unique_docs = retriever_from_llm.get_relevant_documents(query=event.message.text)
     with ApiClient(configuration) as api_client:
         try:
@@ -114,7 +125,8 @@ def message_text(event):
                 messages=[TextMessage(text=answer)]
             ))
 
-        print(answer)
+    log_file.write("bot_answer: " + answer + "\n")
+    log_file.close()
 
 #    with ApiClient(configuration) as api_client:
 #        line_bot_api = MessagingApi(api_client)
@@ -135,4 +147,4 @@ def message_text(event):
 if __name__ == "__main__":
 
     # start web server
-    app.run(port=srv_secrets.srv_port)
+    app.run(port=srv_secrets.srv_port)
\ No newline at end of file